Wanda Gag is transforming! I delivered the finished clay sculpture to Casting Creations. Here are some pictures that show the long process of converting a clay sculpture to bronze. This photo set shows:
- The original clay sculpture
- 2-part rubber/plastic mold (after a wax pour) resulting in...
- hollow wax copy which gets covered with...
- ceramic shell mold
- Wanda's head, cat and other wax parts covered in ceramic shell. Note the cups and "sprues" (tubes) attached to direct the flow of liquid bronze.
After the ceramic shell is set, that faithful wax copy of the clay sculpture is heated and melted away...but the shell holds it's shape. Now there is a void where the wax used to be. The bronze will be heated to 2200 degrees Fahrenheit in a furnace and poured into the ceramic shell molds. Remember the cups? That's the target for pouring from the crucible.
Why is her head cut off? Many bronze castings are made in several pieces. This allows for a more even flow of metal. After all the metal has cooled, it can be broken out of the ceramic shell mold. Pieces are brazed (welded) together and seams ground and polished. If you look closely you can find evidence of seams and grinding on many bronze sculptures.
The assembled sculpture gets sand blasted to reveal a dull gold color. The bare metal is then ready to receive patina, a mixture of chemicals made to react with the surface. Finally, the sculpture is given a clear coat to seal and protect the patina and metal.
Casting Creations is seriously good. Have a look at their website and you'll probably realize you've seen their work. http://castingcreations.us/index.html
Want to learn more about bronze casting? Here's a concise video tour of the process from another foundry in California.